Surfaced-Enhanced Raman Scattering-Active Substrates Prepared through a Combination of Argon Plasma and Electrochemical Techniques

Abstract

In this paper we describe a new surface-enhanced Raman scattering (SERS)-active silver substrate that was roughened using a combination of electrochemical triangular-wave oxidation/reduction cycles (ORCs) and argon plasma treatment to obtain a stronger SERS effect. The mechanically polished Ag substrate was first treated with radio-frequency-excited Ar plasma. The treated Ag substrate was then roughened through ORC treatment in an aqueous solution containing 0.1 M KCl. Finally, this roughened Ag substrate was retreated with radio-frequency-excited Ar plasma. Rhodamine 6G (R6G) was used as a Raman probe to evaluate the SERS enhancement of the various Ag substrates. Encouragingly, the SERS intensity of R6G was increased up to 8-fold, with the SERS spectrum of R6G exhibiting better resolution, when using the fully treated Ag substrate, relative to the use of an electrochemically ORC-treated Ag substrate that had not been subjected to plasma treatment. The improved SERS effects were related to the coalescence of grains and hills as well as the formation of dells and pits during the electrochemical ORCs and Ar plasma roughening processes.